OTTAWA — The Liberal government’s new national security bill is keeping the lower threshold brought in by the previous Conservative government when it comes to terrorism peace bonds, a court order that imposes conditions on suspected terrorist sympathizers.

The Liberals are, however, scaling back the threshold for the more controversial and invasive power of pre-emptively detaining someone suspected of planning an attack — but this arrest power has apparently never been used in practice.

Peace bonds are sought when police don’t have enough evidence to prosecute someone for terrorism offences, but are concerned the person may be inclined to commit one. A judge can impose conditions such as restrictions on movement or a ban on using computers.

The previous Conservative legislation, Bill C-51, loosened the standard needed to obtain a peace bond. The threshold went from needing reasonable grounds to fear someone “will” commit a terrorism offence, to that they “may” commit an offence. The Liberal legislation keeps this C-51 change untouched.

But the bill does change the threshold for a recognizance with conditions, a tool that can allow police to temporarily detain someone without a warrant. C-51 had lowered this threshold from being “necessary” to prevent an attack to “likely” to prevent an attack; the Liberal bill reverts it to “necessary.”

C-51 had also extended the period of time that the person can be detained from three days to seven days, which the Liberals are not changing.

Police have never used the preventative arrest power, according to Public Safety Minister Ralph Goodale’s office. Annual reports going back to 2013 on the provision’s use are published online, showing it’s been invoked zero times.

Terrorism peace bonds have been in regular use by Canadian authorities recently, and the Liberal bill has a clause to start requiring an annual report on how many of them are entered into each year. But there is also debate over how effective these peace bonds are.

Aaron Driver, the 24-year-old killed by police last summer in Strathroy, Ont., had been living under the conditions of a peace bond but still managed to construct a bomb and was allegedly preparing an attack when RCMP officers stopped him.

In 2014, the RCMP had wanted a peace bond on Martin Couture-Rouleau, but prosecutors felt there wasn’t enough evidence. Weeks later he ran his car into two Canadian Forces members in Saint-Jean-sur-Richelieu, Que., killing Warrant Officer Patrice Vincent.

The main problem with peace bonds is there hasn’t been a proper government review of their use, said University of Toronto security expert Kent Roach.

“I wouldn’t want to say that peace bonds don’t have a role to play,” Roach said. “But we really don’t know an awful lot about the effectiveness of peace bonds or whether they’re a justified substitution for a terrorism prosecution.”

With the Liberals planning to create multiple new national security review bodies — including a committee of MPs and senators, and a “super-watchdog” agency that can conduct government-wide reviews — Roach is hopeful peace bonds will start getting proper study.

Tim McSorley of the International Civil Liberties Monitoring Group said he was disappointed to see the peace bond threshold left unchanged, particularly given the roll-back of the preventative arrest threshold.

“If they’re changing one, it should be both,” he said. “The possible conditions in a peace bond are so broad that it makes it easy for someone to break their peace bond, and then be faced with more important charges. So it shouldn’t be easy to impose one; there still should be that burden that they ‘will’ do something.”

In Parliament, opposition reaction to the legislation has been relatively muted. New Democrats have criticized the bill for not scaling back enough of C-51’s changes, particularly on information-sharing powers among security agencies. Conservatives denounced the tightened restrictions on preventative arrests, calling it a “dangerous step back.”

The massive piece of legislation was introduced in the final week before the House of Commons breaks for summer recess, meaning it won’t receive serious study until the fall.

Along with its adjustments to C-51, the bill gives expanded powers to Canada’s electronic spy agency, sets up new rules for how the Canadian Security Intelligence Service can handle data, and overhauls the government’s security review structure.